Differences in mandibular distraction osteogenesis after corticotomy and osteotomy

Abstract

Corticotomy or osteotomy was performed on opposing sides of the mandibles in 18 goats. A custom-made distractor was used to lengthen the mandible at a rate of 1 mm/day for 10 days (total 10 mm elongation). Six goats were sacrificed respectively at 2, 4 and 8 weeks after completion of distraction. The distracted calluses were harvested and processed for radiographic, histologic, and scanning electron microscopic evaluation as well as Ca/P ratio analysis. The regenerate bone in the corticotomy side showed more bone formation and earlier mineralization than in the osteotomy side. The results of this study suggest that preservation of intramedullary vessels is beneficial to bone regeneration following mandibular osteodistraction, and that performing corticotomy may be a simple but effective way to promote the maturity of the distracted callus and shorten the time for fixation.

Fig. 1

Mandibular radiographs at sacrifice, showing the differences in radiodensity between the corticotomy (CO) and the osteotomy (OS) sides. Note greater formation of periosteal callus (arrows) on the osteotomy sites at 4 and 8 weeks’ postdistraction. (A) 2 weeks. (B) 4 weeks. (C) 8 weeks.

Fig. 2

Histological photomicrographs of the regenerate bone in the distraction gap. (A) Corticotomy—2 weeks (HE×40). (B) Osteotomy—2 weeks (HE×40). (C) Corticotomy—4 weeks (HE×40). (D) Osteotomy—4 weeks (HE×40). (E) Corticotomy—8 weeks (HE×100), showing that mature lamellar bone and fatty marrow filled the newly reformed medullary cavity.

Fig. 3

SEM photomicrographs of regenerate bone in the centre of the distraction gap. (A) Corticotomy—2 weeks (original magnification ×50). (B) Osteotomy—2 weeks (original magnification ×50). (C) Corticotomy—4 weeks (original magnification ×200). (D) Osteotomy—4 weeks (original magnification ×200). (E) Corticotomy—8 weeks (original magnification ×200). (F) Osteotomy—8 weeks (original magnification × 50). Note an interface and some differences in density between the new bone (NB) and the original bone (OB).